Process for forming ends of tubing



Aug. 11, 1964 w. A. MIESZCAK 3,144,070

PROCESS FOR FORMING ENDS OF TUBING Filed Nov. 10, 1961 2 Sheets-Sheet l INVENTOR. W/u. IAM AMreszaznK mob,

g- 11, 1964 w. A. MIESZCAK 3,144,070

PROCESS FOR FORMING ENDS OF TUBING Filed Nov. 10, 1961 2 Sheets-Sheet 2 INVENTOR. WILLIAM A. MIESZ ZHK United States Patent 3,144,070 PROCESS FOR FORMING ENDS OF TUBING William A. Mieszczak, 1922 E. 2nd St., Erie, Pa. Filed Nov. 10, 1961, Ser. No. 151,502 Claims. (Cl. 153-34) This invention relates to forming machinery and processes and, more particularly, to a process of forming an end on tubing.

The process of drawing rod, wire, or tube utilizes the function of reducing the outside diameter of a rod, wire, or tube by passing the selected item through a die of smaller diameter. When tube is drawn, a mandrel or plug is inserted through the inside diameter of the starting tube. The result is that both the outside diameter and the wall thickness of the drawn tube are smaller than that of the starting tube.

To permit the starting end of the tube, wire, or rod to pass through the draw die, this end must be smaller than the outside diameter of the starting tube, wire, or rod. Reducing the end to a smaller size has come to be known as pointing; various methods have been utilized to make the point. The most common of these in use today is rotary swaging. This is accomplished in machines designed for the purpose of reducing the outside diameter of a round shape or for the forming of a round end on other shapes. The process is relatively slow, much physical eifort is needed to perform it, the cost of dies is relatively high, and there are other disadvantages which many users of such machines have tried to eliminate over the years.

The disadvantages of rotary swaging have been particularly undesirable to the tube drawing industry. Many mills have used presses and dies to impact a point on the tubes which they process. Depending upon individual successes, some of these mills have made limited use of press pointing.

These dies, however, were designed in erroneous principle. As a result, there are limits to their development and application. In addition, the cost of maintaining pointing equipment is higher than need be and the problems of production application have not been as fully solved as is desirable. The error in principle is that a tube, when placed under equal pressure in a flat plane, will assume an elliptical shape of symmetrical dimension. This is not necessarily so; with rare exceptions foreseen but not yet determined, the true shape is that of a deformed ellipse approaching the outline of the Arabic figure 8.

Discovery of this error led to a new concept of deforming a tube to make a point. The need for opposed fingers to fold the tube was eliminated. In turn, a more simple die set became a possibility. Together with this possibility was that of almost certain predictability of point concentricity, uniformity, and straightness of the used portion of a point made in the die set of simpler design.

Stimulated by these potential advantages, a die set evolved as herein disclosed which has the following advantages:

(1) Elimination of fingers for folding the tube permits the use of fiat pressure plates to yield the starting deformation.

(2) The second deformation becomes only a matter of starting the folding of the tube. This is accomplished by one or more embosses formed in the blade or the die or the blade and die of the die set.

(3) Compacting of the point follows in the usual manner excepting that the length of blade stroke is reduced to a minimum.

(4) Because of the simple die design, the use of hy- 3,144,070 Patented Aug. 11, 1964 ice draulic power becomes feasible with the following advantages:

(a) Production rate can be maintained equal to that of a mechanical punch press.

(b) Machine requires less floor space and less head room.

(c) Set up times for die set changes are minimized.

(d) Forming and compacting of points are done by squeeze pressure rather than by impact force.

(2) Point characteristics are more predictable, more uniform, and more consistently reproducible, point for point.

(f) Maintenance of the die set is minimized.

(g) Standardization of machine components design permits more accurate and reliable construction of machines for special needs.

(It) The machine is well suited to mechanizing load and unload, automatic cycling, and other requirements necessary to eliminate the need of a full time operator.

The machine according to the invention consists of a frame and two cylinders with pistons therein attached to rams of suitable capacity. Either of the rams in the machine can be arranged vertically or oneof them could be vertical and the other horizontal. The cylinders may be actuated by a suitable air hydraulic circuit, a simple hydraulic circuit, or a simple air circuit operating all of the controls. The frame of the machine can be cast integral with the cylinders or may be of the side plate to cylinder platen construction. The base of the frame may have a bottom platen to include the necessary dies for carrying out the operation disclosed herein.

More specifically, it is an object of the invention to provide an improved method of forming an end on tubing.

Another object of the invention is to provide an improved die for forming a point on the end of tubing.

Still another object of the invention is to provide an improved die and machine combination for forming the end of tubing.

A further object of the invention is to provide an improved combination die for tube forming.

Yet a further object of this invention is to provide an improved method for forming tubing.

A still further object of the invention is to provide a die and method for forming tubing which is simple, efficient, and economical.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawings and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions, and

minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings:

FIG. 1 is a side view of a punch and die arrangement according to the invention;

FIG. 1A is a schematic view of the press and control circuit according to the invention;

FIG. 2 is an isometric view of a tube having a point formed on the end thereof according to the invention;

FIG. 3 is a View of the die in open position showing the vertically movable part and horizontally movable part with a tube therein;

FIG. 4 is a view of the die at the second stage showing the horizontal portion moved in to form the modified ellipse before the vertical portion moves;

FIG. 5 shows the die at the next stage of the process with the vertical part starting to move down;

FIG. 6 is a view of the next succeeding stage; and

FIG. 7 shows the completed tube point.

- Now with'more particular reference to the drawings, a press is controlled by an air hydraulic circuit 11 best shown in FIG. 1A. The press has a first vertical cylinder 12 and a second cylinder 13 for giving horizontal motion. In agtual practice, these two cylinders will both have their pistons preferably operating in a vertical direction; however, the second cylinder 13 could operate in a horizontal direction to move a horizontal die 15 in a direction perpendicular to .the movement of a punch 16. The fixed die 14 has the horizontal die 15 supported adjacent thereto.

The press vertical cylinder 12 has a cam 24 fixed to its piston rod and the cam has a vertical surface 25 which rolls along the outer periphery of a fixed roller 21. The fixed roller 21 is supported between brackets 22 on an axle 23 and it restrains the cam 24 against movement to the left as the piston of cylinder 13 moves the cam 24- up and down. i

The cam 24 has a second flat surface 26 on the opposite side thereof from the surface 25 and this surface rolls along the outer periphery of a roll 31 which is attached to the movable die 15 by means of the axle shown. It will be seen that the cam has the two generally parallel surfaces 25 and 26 and an inclined surface 27. The cam is, in effect, wedge shaped.

The horizontal die 15 slides back and forth on a track 32 which is a horizontal part of the fixed die. The horizontal die 15 is urged to the left by a spring 33 to bring the roller 31 into contact with the cam 24 which has one end engaging an abutting surface 35 on the fixed die and the other end engaging an abutment 36 in the horizontal die.

The punch 16 has a contoured work surface 41 which is generally hemispherical in shape and has a ridge 42 extending therealong parallel to the axis of a pipe 17 and perpendicular to the path of movement of the horizontal die 15 and slightly to one side of the radius of the cylindrical surface. That is, the ridge is laterally displaced from the .vertical axis thereof. In operation, this ridge breaks the tubing to start it to form the desired shape.

The fixed die 14 is generally L-shaped having a vertical working surface '50 and a horizontal work surface 51. The horizontal surface 51 has a contoured surface 52 hemispherical in shape like the working surface 41. A ridge 53 is formed in the surface 51 parallel to the axis thereof and of the pipe or tube 17 and displaced to the side thereof opposite the side to which the ridge 42 is displaced. It will be seen that when the dies are closed, the two contoured surfaces 41 and 52 together form an enclosure which is substantially equal in volume to a corresponding volume on the finished end of the pipe.

The pipe 17 is shown having a body portion 60 which may be of any desired length on which a point is to be made. When the pipe 17 is put in the die as shown in FIG. 3 and the second cylinder 13 brought down to move the cam 24 to the position shown in FIG. 1, this will move the horizontal die 15 to the position shown in FIG. 4, forming a modified ellipse. The extent of flattening of the pipe at this point can be controlled by adjusting the position of the roller 21 so that the cam will move the horizontal die 15 a greater or lesser amount toward the surface 50. V

In the next stage, the punch 16 is brought down through the position shown in FIG. 5. This forces the pipe to change its shape from a modified ellipse as it is forced down into the contoured surface 52. As the punch moves .down, it causes the ridges 53 and 42 to bite into the pipe and start to collapse at the correct points as well as to hold it against slipping, thus scoring it. Then as the punch 16 is further brought down toward the track 32, the end of the pipe will be forced by the contoured surfaces to deform to the shape shown in FIG. 7.

It willbe seen that the punch is of a width equal to the spacing between the horizontal die 15 and the fixed vertical working surface of the fixed die 14. It will also be seen that the end of the tube will be formed with a tapered portion 61 generally frusto-conical in shape with a reduced size end made up of the generally double 8- shaped bend, the 8 having outer folds 63 and intermediate folds 64 connected by inner folds 65 to form the S-shapes. Should material of greater hardness be formed, the S- shaped end may vary to the shape shown in FIG. 7.

A hydraulic circuit made up as shown in FIG. 1A may control the dies. The circuit shows a motor 77 which drives a suitable hydraulic pump 76 connected through a check valve 75 to a pilot operated four way valve 74. The pilot operated valve 74 connects the fluid under pressure from the check valve 75 selectively to the second cylinder 13 or the vertical cylinder 12, depending upon the position thereof, through a sequence valve 73 and a pressure reducing check valve 72 connected as shown. The second cylinder 13 will move the horizontal die 15 inward until it strikes a limit switch 78 which will stop it. At this position, the die 15 will be so spaced from the surface 50 that the punch 16 will have room to move freely therebetween. Then the vertical cylinder will be moved down in sequence to distort the elliptical shaped end of the pipe to form the end of the tube to the double 8 shape as shown. This is a symmetrical compact shape which can be effectively grasped by a pulling tool.

The foregoing specification sets forth the invention in its preferred practical forms but the structure shown is capable of modification Within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as, follows:

l. A method of forming a tube comprising providing a generally L-shaped die having a cavity generally hemicylindrical in shape in one leg thereof adjacent the other leg, forcing the end of a pipe toward said leg adjacent said leg having said cavity to form said pipe end into a modified ellipse with the sides of said ellipse extending inwardly toward each other, and restraining said pipe end to the width of said ellipse and exerting a second force thereon, causing said sides of said ellipse to engage each other along a substantial length thereof and containing said force to compress a part of said pipe end into said cavity.

2. The method recited in claim 1 wherein a concentrated force is exerted along the axis of said pipe at a position offset from the vertical radius thereof and a similar concentrated force is exerted from below along the line offset from the first line during the time said second force is exerted whereby said pipe is scored during the compressing operation and caused to collapse into said cavity in a predetermined shape.

3. A method of forming an end on a pipe comprising compressing said pipe laterally to form it into the shape ,of a modified ellipse with the sides of said ellipse extending inwardly toward each other, restraining said pipe to the width of said ellipse, and exerting a second force perpendicular to said first force to continue to deform said pipe end, causing said sides of said ellipse to engage each other along a substantial length thereof and continuing said force into a compact, generally cylindrical shape.

4. The method recited in claim 3 wherein said second force is exerted on said pipe end in a generally cylindrical pattern from opposite directions perpendicular to the minor axis of said ellipse.

5. The method recited in claim 4 wherein a concentrated force is exerted on said pipe end from each side thereof perpendicular to the minor axis of said ellipse during the time said second force is being exerted whereby said pipe end is scored.

(References on following page) 5 References Cited in the file of this patent 2,589,142 UNITED STATES PATENTS 3,068,929

352,656 Parker Nov. 16, 1886 1,994,725 0mm Mar. 19, 1935 444,480 2,044,322 Oliver et a1 June 16, 1936 567,355

6 Rotheroe Mar. 11, 1952 Rowell Dec. 18, 1962 FOREIGN PATENTS Germany May 21, 1927 Great Britain Feb. 9, 1945 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 144,070 August 11, 1964 William A. Mieszczak It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below In the drawings, Sheets 1 and 2, line 1 of the heading thereof, for W, A, MIESZCAK", each occurrence, read W, A, MIESZCZAK column 4, line 54, after "comprising" insert causing a first force to be exerted on said pipe and thereby Signed and sealed this 16th day of February 1965. v

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A METHOD OF FORMING A TUBE COMPRISING PROVIDING A GENERALLY L-SHAPED DIE HAVING A CAVITY GENERALLY HEMICYLINDRICAL IN SHAPE IN ONE LEG THEREOF ADJACENT THE OTHER LEG, FORCING THE END OF A PIPE TOWARD SAID LEG ADJACENT SAID LEG HAVING SAID CAVITY TO FORM SAID PIPE END INTO A MODIFIED ELLIPSE WITH THE SIDES OF SAID ELLIPSE EXTENDING INWARDLY TOWARD EACH OTHER, AND RESTRAINING SAID PIPE END TO THE WIDTH OF SAID ELLIPSE AND EXERTING A SECOND FORCE THEREON, CAUSING SAID SIDES OF SAID ELLIPSE TO ENGAGE EACH OTHER ALONG A SUBSTANTIAL LENGTH THEREOF AND CONTAINING SAID FORCE TO COMPRESS A PART OF SAID PIPE END INTO SAID CAVITY. 